Automatic simulated two pointer glide path for ground training



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p c. w. MULLER AUTOMATIC SIMULATED TWO POINTER GLIDE PATH FOR GROUND TRAINING Filed March 1, l940 p 1943- c w. MULLER 2,448,544

AUTOMATIC SIMULATED TWO POINTER GLIDE PATH FOR GROUND TRAINING ,Filed March 1, 1940 4 Sheets-Sheet 2 //v VENmR Sept. 7, 1948. c. w. MULLER AUTOMATIC SIMULATED TWO POINTER GLIDE PATH FOR GROUND TRAINING 4 Sheets-Sheet 3 Filed March 1, 1940 aRNFVS I l/EN r01? LLER LHI C421 14 Nu 0 O I m ll. ulaN $29 C. W- MULLER AUTOMATIC SIMULATED TWO POINTER Sept. 7, 1948. v

GLIDE PATH FOR GROUND TRAINING 4 Sheets-Sheet 4 Filed March 1, 1940 Avaszvv-OR LL. E1?

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2m 00 V K M J QA simulated landing runway corresponding to particular altitudes transmitted from the student to the instructor in a manner hereinafter more particularly described.

In my copending application No.v 319,498, filed February 17,1940, I have disclosed a means for mechanically actuating an electrical signalling system for automatically giving aural signals of a character and volume controlled by the position of the recorder on the record table and this application forms a continuation in part of the above identified application. Such application has matured into Patent No. 2,438,126, dated March 23, 1948.

It is an object of this invention to provide in.

an aviation ground training system a ground trainer controllable in a manner to simulate the flight of an aircraft, a course recorder directionally controlled by the ground trainer and movable relative to a record surface at a velocity pro-- portional to the simulated flight velocity of the trainer, a signal system controlled by the course recorder to give an aural or visual signal of a character, dependent on the position of the course recorder on the record surface relative to a pre-.

determined course on the record surface, a means to simulate the vertical descent of the trainer along a predetermined glide path in a vertical plane, parallel to the said predetermined course on said record surface and marker beacon simulating means actuated by the recorder for indicating predetermined positions of the course recorder-along said predetermined course on said record surface.

It is a further object of the invention to provide a mechanical means, operated by an aviation ground trainer course indicator for actuating a visual indicator to indicate the departure of said course indicator in a horizontal plane from a predetermined course on a supporting reference surface. I I

A further object of the invention is the provision of .atwo pointer, visual, glide path indicating system for aviation-ground trainers, in which the recorder mechanically controls the indication of said pointers.

A further object of the invention is the provision of a system for simulating descent of an aviation ground trainer along a predetermined cordance with the simulated departure of the trainer-from a predetermined-course encompassed within the limits of an assumed landing runway localizer beam.

Other objects of the invention will become apparent by reference to the specification and the appended drawings forming a part thereof in which:

Fig. 1 illustrates schematically the essential apparatus and electrical circuits for forming 'a two pointer glide path indicating system to-enable blind landings, in accordance with the Bureau of Standards Blind Landing system,-to be simulated in an aviation ground trainer;

Fig. 2 is a side elevation partly in section of the mechanical indicator control means used in the system illustrated in Fig. 1;

. Fig. 3 is a view showing a gearing detail for use in the device of Figs. 1 and 2; and

Fig. 4 is a schematic illustration of a modified form of the system illustrated in Fig. 1 in which an aural signal means is incorporated.

Fig. 5 illustrates the trace left by the course indicator on a record sheet after making an in- 4 strument landing employing the device of Fig. 1 or Fig. 4; and

Fig. 6 illustrates a side elevation of the record sheet of Fig. 5 illustrating schematically the simulatedflight path of thetrainerin making an instrument landing employing the device of Fig. 1 or Fig. 4.

The Bureau of Standards Blind Landing system comprises a radio transmitting station which radiates a radio signalling field formed by two directional overlapping signal fields, extending along the axis of the landing runway in such a manner that in a narrow zone aligned with the runway, a continuous On course signal will be heard, while if off course to either side of the zone. an A or N signal will be heard in the radio receiver tuned to the runway localizer beam frequency. Keyed I to T or other type signals may be used in place of the A and N signals. By keeping in the On course signal zone, the pilot knows that he isdirectionally aligned with the airport landing runway. The so called runway localizer beam is thus identical in function with the conventional radio range signal system and differs therefrom only in the number of On course, signal legs and in the width of the On course. signal zone., In addition to aural reception of signals, a visual indicator is also used, indicating by its deflection, whether the fiight is On course or to the right or left of a course, aligned with the landing runway. A second radio transmitter transmits from a directional antenna, a signal field having an elliptical pattern in the vertical plane, aligned with the land.- ing runway, the lines of constant signal strength forming one or more curved parabolic glide paths. intersecting the landing runway at a desired point thereon. A glide path receiver actuates an indicator, having its pointer horizontal and intersecting the pointer of the runway 10- calizer beam pointer. The glide path indicator indicates whether the aircraft is above or below the proper glide path. The combination of the two indicators serves to indicate the position of the aircraft, both with respect to the landing runway and the glide path and the pilot attempts to maintain the pointers intersecting at the center of the indicator dial. Marker beacon transmitters are arranged to indicate at least one fixed distance from the airport and to mark the field boundary and these transmitters radiate a signal field, in narrow vertical planes, affording additional positional information and serving as a check on the proper altitudes at the respective beacon points, since the glide path should inter- :ect the outer marker beacon. at a definite altiude.

In accordance with the invention, the means to simulate the runway localizer beam indicating system. illustrated in Figs. 1 and 2, is as follows:

The aviation ground trainer generally indicated by the reference numeral l and shown in dotted. lines is controllable in the manner above described and as it changes its azimuth heading, it rotates the rotor of the Selsyn transmitter S, which by conductors S1, transmits an equal motion to the rotor of the "Selsyn receiver S2, which controls the azimuth heading of the course recorder 3, in its travel over the surface of the record table 2, in the manner above described. The field winding supply to the Selsyn transmitter and receiver units is not illustrated since this type of electrical motion transmission is well known in the art and needsno further comment. The recorder 3 is propelled by motors 4 over the record-tabla Ziat as constant speed whicmmam be adiust'e'd tet represent: to some dcsired fscal'estlre simulatedvelooity inflight ofthe groundttrainer I in the manner" above-described The marker roller wheninked, serves to tracethe eourseot the; simulate d2 flight ofthe trainemupomassuitable man or"recordsheet.- wherecordkr'l t-migz Zl has "a -vert'ical stem '6 secured thereto vertical alignment with. thesteering axisscf thewnmrker wheel 55'- The stem 6=projects into the open side are: U-shaped charmel memberfl; parallel to he surtac'eof'the record table 2; channel 'lis secured at its inner 'end' to the lower end ofia shaft 8, rotatably mounted in a ballbeari ng 'fi, suitably mounted im at Boss at the outer and of a light metal frame" HI; also :arrangeifin parallel spaced relation withthesurface ofi' table The frame I 0 is rigidly mountemby the support l fi on any'suitabrestr'ucture oot-shown) so that the frame I U remai-ns stationary. The shafirt'i's hoflow and its axis intersects-the surface ot'the-table Z; at thapointv; assumed tube the'l'ocati'on of the runwayloca-lizer "beam transmitting station; It will be seen=thatany-rotatiomofi the recorder 3 about the oint D will: cause rotation of" the arm I and shaft 8.

A;sleevalrlaoi' msulatme m-atental is secured to the shajit 8 and has: contact rarmsr Iiiana M securedi. thereto in spaced-relation: andC rotatable therewith; The: contactarmek! and Marc. each respectively electrically connected to' slip ri'ngs 1-5 and m, which in: tum'arerespectiveiyengaged by the brushes W and I 8,: which are: fixed to an insulated "mounting: bracket: m scoured. to fram-e m; The contact arm senseless amarcuatemetal contact v2 K1,:mountediom at blockfzl, of insulating material; The contact amr Hi1. cngagesi an electrical resistance: winding" 25 or arcuate: shape mounted on thc-lirrsnlatingmblock23o Thei'blocks M and are each secured: to a. bracket 4', mounted onframe ill-a.

As seem 1;. the. resistance Zt isriionnested at oneiemt byza conductor 36; to:the-posiitivetermicial of abattery 3t, otftwo or more oells connectedinserics; Thewother end. oftheriresist 1 ance 22' is connectedfibm conductor natozthe nceative: terminal ofithe battery M. A? neutral con;- ducto-r 33 connected between the-positivm and negative terminals of the battery; connectszto one terminal of a -zcroi. center? type galvariometer 4', the otherterminalv lot which is' connected by conductorfii, through the -mediumof brush t8 amtsli-p ring lfi -iFigzzltocontactarm t-l l; The contact arm 14 is axially aligncd'mtlr thcIons gitudinal axis of therchammel vmemherfl and its relation to the resistance are such, that when thechannel member 1 is; aligned "with the axis of the On: course signal. zone or thel localizer beam, schematically illustrated in Fig.1; thescontact arm M will beat thamid-pointofthe resistance 22 (and there will: :be a bail-'ancerof resistancezin each branch .circui-t-frormthe batteryiiil and the pointer-oat galvanomcterfl- 'will'remain in the zero position; By suitably 1 arranging the polarity of the ealvanometer' E4;.when:t1ie re corder Scauses the arm:'l-to;-rota1te clockwise,

as seen in Fig. 1, the current flow in conductor 33 will 0311861116? pointer '-of"galvancmeter'= 34 to move toward the left,- indicating'thatthe recorder is oil? the runway localizcrbeam; to the alert. and similarly counterclockwlser rotation or: channel member Twill cause deflection oftl'ie: galvano'm eter 34 to the-right-of thc'zero positiom It is seen that movement ofi' contact arm? :either direction from the center positionzoniresistance 6 2-2 will causean mbalance in :resistance Kin the branch circuits and conductor -"33c will carry a current in a direction and-of a magnitude; depending err-the magnitude and direction of movementai thecomtact arm M from the: central position:-

"The zero centerealvanometer'fl is mounted on theinstrument board o1 theitra-iner 1" and so long as the simulated flight course of the trainer remaihsparallel wltl l the simulated: runway locali zer beam drawn'ontherecord surface; the recorder 3 will cause no rotation of the arm 1 about the axiaof shaft-8 'andthe contact arm- MWill rcmain irrthe central position on resistance 22, causing thednd-icatorfl to readzero or On course. 'I-he recorder i isg however, free to move radially inwardor outward with respect to the axis of rotation of shaft 5 sincethe stem 6 of the recorder-"3 may slide in the channel 1. If the recorder 3 and the'corresponding simulated traincr flightJ-shoul'd vary, either-to the right or left of" the simulated runway localizer beam, On course posi tionr thc .galvanometer will indicate the" di re'ctionwand approximate magnitude of suclrrdeviation, so that the studentmusttiexecute a: correcting control. on 1 the trainer. "to: return to theiproper" course, aligned with the. simulated landmg-runway. 1 i

'Elrcwstructureforiindicating the position "of the ground; trainer in; a simulated descent relative to an: assumed glide :path is as follows: 4

seer r in'l' igz' 2, the: stem B of the recorder projects within the channel member 1 and the stemzi tomaymove radiallywith respect to the axis of rotatiomof shat-t ll. The stem 6 hasconnccted tl rcreto a small "stranded flexible cable '38, whiclaipasscsover a smailaguide roller. 39:, suit ah lytmountedein':jewelled hearings in the channel membcrd. The nable' flawpasses upward through thchollowzshaft 8 and coaxial therewith oversaw-small ."guide pulley 40, suitably pivotally moimtcdwon aswivelled head M, rotatably mountedrclative {to thelshaft; my, a suitable ballbearma; Thegcableflrthenwraps around a cable drum .42 iand; its terminal end ,1 is: secured thereto. fil hmcable 'drum fills-secured to: the vertical shaft 43 {of ar-variablemesistanoez unit 44 mounted by meansoofrbrackets 48-011 the frame 10;. A. light hair:snr nexmbiasesthe shaft 43 and drum 4 2 to rotate isma counterclockwise direction to take up cahlerslack andtorotate the: shaft 43, to thereby varying-resistance of unit. It is thus seen that the recorder in moving inward toward point- D willxzcreate slack in cable 36;,wh-ich will immediately cause'hair spring 49 to rotate shaft 43 to takerup theslackin the cable and to actuate the! variable resistor: unit 44. The rate of movement of themesistorncontrol shaft 43 will equala to-therxvelocity of the recorder 3 and hence rproportional to the simulated velocity of the-trainer, :as the recorder moves towardxpoint D orrtheurecordttabled in alignment with the simulatedxlandingarunway. V

' As-seen inzElga-l, theresistanceunit 44 com ,prises a-=resis tance winding 45, contact by the contxtctarm-AG; rotatab-le'with thcshaft 43. The resistance winding is connected by the conductor 411w the vconta ct strip' zll; whichin turn-is engaged by i the contact am i l 3,; rotatable with shaft-=8i and aligned with-thelongitudinal axis orthnrchanncl'membcr'l. The'arm [3' is conand conductor 48 =t0- the rotatable resistor contac-t arm ill; which-contacts the resistance winding H. The contact arm 49 1s rotated by means of shaft 50. The resistance is connected in series with a galvanometer 52 having a horizontal pointer and cooperating with a dial in common with the zero center galvanometer 34, the normal planes of the pointers being at right angles to each other. The galvanometer 52 is connected by means of a conductor 53 having an adjustable rheostat 54 inserted in series therewith to one terminal of a battery 55, the other terminal of which is connected by means of conductor 56 to the contact arm 46 of the resistor unit 44.

The shaft 50 of the resistor contact arm 49 has a pinion gear 60 mounted th'ereon and engaged by a rack 6|, reciprocable by means of a metallic bellows 62, connected by a conduit 63 to a tank 64 forming a part of the altitude simulating means in the trainer. The tank 64 is adapted to be evacuated by a pump controlled by the climbing attitude of the trainer and the simulated throttle setting so that the pressure within the tank simulates the changing atmospheric pressure during a climb and its final pressure corresponding to an assumed altitude, a conduit 65 connects to an altimeter on the trainer instrumerit board to indicate the instant simulated altitude and a rate of climb indicator may be similarly connected to the tank. When the trainer is placed in a descending attitude, the pressure is gradually restored to atmospheric pressure. The means for evacuating the tank, the control means and the altimeter have not been illustrated in the drawings since they are well known in the art and form a part of the standard equipment of trainers of the Link type above'noted.

The operation of the device is as'follows: As the recorder 3 approaches the assumed airport D (Fig. 2) along the course of the runway localizer beam, the resistance of unit 44 will be decreased at a rate proportional to the simulated velocity of the trainer, while the pressure responsive device 62 will cause the resistance 5| to be increased at a rate equal to the simulated rate of descent of the trainer, since as the pressure in the tank 64 returns toward atmospheric pressure, simulating descent of an aircraft, the bellows 62 will expand and move upward, causing resistor arm 49 to move in the resistance increasing direction. By adjusting resistance 54 above a predetermined altitude, a certain minimum value of the resistance 5| will be introduced in series with the resistance of unit 44, galvanometer 52 and battery 55. A current will flow such that the galvanometer pointer will be in the middle of its scale, which is the zero position. If now it is assumed that the trainer descends for a simulated landing along the simulated glide path beam, indicator 52 will remain in the zero position as long as the resistance 45 and resistance 5| are inversely varied in equal amounts, but if the rate of descent is too great, the resistance 5| in series with the battery 55 will increase an amount which will increase the total resistance in the circuit and the current will accordingly decrease causing the pointer of galvanometer 52 to drop, indicating that the simulated position of the trainer is below the simulated glide path. In a similar manner if the rate of descent is not sufficient, the total resistance in series with the battery 55 and galvanometer 52 will be decreased and the current will increase, causing the pointer of galvanometer 52 to move up from the neutral position to indicate that the simulated position of the trainer is above the simulated glide path. The student endeavors to maintain the pointers of galvanometer 34 and 8 galvanometer 52 intersecting at the middle of the dial and the shift of the point of intersection indicates, for example, that the simulated flight is to theright of the landing runway and above the glide path, when the point of intersection is in the upper right hand quadrant of the dial and corresponding indications are given in the other quadrants. The glide path can thus be followed and the landing may be assumed to be accomplished when the altimeter reads zero, or if desired, a signal lamp maybe flashed or the trainer power supply cut off when the altimeter is in the zero position to indicate simulated contact with the ground. i

The effect of acurved glide path is obtained by varying the value of the units of resistance per unit of angular deflection of either one or both of resistance windings 45 and 5|, and this variation may be logarithmic or otherwise to imitate as nearly as desired the actual glide path inuse in various blind landing systems. Where the curved landing beam is to be simulated, the'student must continually change the rate of descent to stay on the simulated landing beam; One type of landing beam glid path is illustrated at G,inFig.2.

In order to simulate the marker beacons in use with the Bureau of Standards and other blind landing systems, as seen in Figs. 1 and 2, the invention utilizes two pairs of olosey spaced metal bars or contacts 69 and-1|] respectively, imbedded in the surface of the record table 2 at spaced points along the axis of the landing runway and spaced at scale distances representing thefield boundary and a distance of two miles or other desired value from the fleld'boundary, measured from point D, the assumed localizer beam and glide pathbeam transmitter station points, on the record surface. The metal bars 69 represent the field boundary marker beacon transmitter station point, indicated by the point I and the metal bars 10 represent the outer marker beacon station indicated as O. The metal bars 69 are connected in series with a signal lamp 66 and a battery 61, so that when the metal recorder marker wheel passes over the bars it will complete the circuit to lamp 66. The metal bars 10 similarly are arranged in a series circuit with a signal lamp 68 and battery 61, so that when the metal recorder marker wheel passes over bars 10, it will complete the circuit to lamp 68 and the light will indicate the position of the recorder at the outer station 0. Simple contact switches may beused in place of the bars 69 and Hi. The student in making the simulated trainer landing is apprised of a known simulated distance from the field when the recorder flashes *the outer beacon signal lamp 68 in the trainer cockpit and he should then, if not on the glide path beam, intersect the same at a predetermined simulated altitude of say, eight hundred feet. Assuming the 'descentis being made along'the glide path beam, when the recorder flashes the inner field boundary marker beacon lamp 66 in the trainer cockpit, the student must then close the throttle shortly thereafter, in order to simulate a proper landing. I

In the device of Figs. 1 and 2, if the recorder is in a position to the righ'tor left of the range of the localizer beam zone, the resistor arm I4 will move out of contact with the'resistance 22 and the contact arm l3 will move out of contact with the contact strip 20, so that both the'localizer beam indicator and the glidepath .indicator 52 will be rendered inoperative. l

raisethe trainer hood-or a signal actuated by the altimeter may be employed-to indicate the completion of the simulated landing, and the point of landing g, is marked by the instructor. From the altitude readings the instructor may easily determine the glide path of the'simulated descent, and the point gof the assumed landing on the record sheet indicates whether or not the simulated landing was within the prescribed limitsof the landing runway. The altitude should be about eight hundred feet at the outer marker beacon station, and about forty feet at the inner marker beacon point located at the airport boundary when passing thereover during the simulated descent of the trainer.

Fig. 6 illustrates schematically the flight maneuvers executed by the trainer duringthe instru ment landingtraced in Fig. 5, and the reference indicia correspond to the indicia employed in Fig. 5. The illustration is believed to be sufficiently clear when taken with the description of Fig. so as not to require any further description.

While a simple mechanically operated signalling system for effecting simulated blind instru-- ment landings in an aviation ground trainer has been illustrated, many modifications within the scope of the invention, as defined by the appended claims, will become apparent to those skilled in the art.

I claim: l

1. In a system for simulating blind landings in aviation ground training apparatus, a ground trainer for simulating the flight of an aircraft, a reference surface, a course indicator movable relative to said reference surface at a velocity proportional to the simulated flight velocity of said aircraft and directionally controlled by said trainer, a signal system for indicating the position of said course indicator relative to an as-. sumed landing runway on said reference surface including an indicator mounted in the cockpit of said trainer and control means for said signal system, a pivoted arm actuated by said course indicator and having its pivotal axis intersecting said reference surface at a desired point .on said landing runway axis, a connection between said arm and said signal system control means, a second signal system for indicating the instant positionof said aircraft in said simulated flight relative to a simulated glide path, including a glide path indicator, an altitude-simulating means controlled by said trainer, a means responsive to the simulated rate of descent of said aircraft actuated by said altitude-simulating meansfor causing said glide path indicator to indicate in one sense of indicatiomand means controlled by said course indicator in accordance with the simulated velocity of said aircraft for effecting the indication of said glide path indicator in the opposite sense of indication, the net deflection of said glide path indicator representing the relative position of said simulated aircraft descent relative tosaid simulated glide path,

2. A blind'landing indicating'system for aviation'ground trainers, comprising a signalling system for-simulating a landing runway localizer beam indicating device and a control means for said signalling system, a reference surface, a course indicator movably supported on said surface and adapted to have a controlled motion proportional to the simulated velocity in flight of an aircraft and in an equivalent direction thereto, a connection between said course indicator and said signal control means for actuating said signal control means in response to deviation of said course indicator from a predetermined course on said reference surface representing the said landing runway,- a second signal system for'indicating simulated descent of said aircraft along a predetermined simulated glide path, and a control means forsaid second signal system actuated by said course indicator in accordance with the velocity thereof and simultaneously operated in accordance with the simulated rate of descent of said aircraft.

3. In a two pointer glide path indicator system for aviation ground trainers, a course indicator for indicating the simulated course of an aircraft, a landing runway localizer beam indicator, a control means for said indicator, a mechanical means connecting said course indicator and said signal control means and responsive to deviation of said course indicator from a predetermined course parallel to a simulated landing runway to cause said indicator to indicate said deviation, a glidepath indicator for indicating the simulated path of descent of said aircraft relative to a predetermined simulated glide path including a control means for said glide path indicator, a means responsive to the simulated rate of descent of said aircraft, an operative connection between said glide path indicator control means and said rate of descent responsive means and a connection' between said glide path indicator control means and said course indicator for actuating said glide path indicator in accordance'with the velocity of said course indicator.

CARL W. MULLER.

REFERENCES CITED "The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,070,178 Pottenger Feb. 9, 1937 2,110,869 Crane Mar. 15, 1938 OTHER REFERENCES 

